In article <botced$chd$1 at smc.vnet.net>,
Jens-Peer Kuska <kuska at informatik.uni-leipzig.de> wrote:
> oh with
>
> "why not _start_ with a
> cellular automata, modeling the
> microscopic behavior of fluid molecules"
>
> you can also make a cow from the beef ?
For an intelligent person, Jens, it seems you have missed the whole
point of NKS.
> The Naver-Stokes equation is an approximation,
> a numerical model is an approximation to this
> approximation and a CA is an approximation to this
> approximation.
No, No, No ...
> And now tell me why the approximation,
> of the approximation, of a approximation is a good
> starting point to describe the *real* process without
> an approximation.
Because this is _not_ what NKS is proposing.
> Where is the source of all the information that is
> lost in during the various approximations if you start
> not with the original ?
But what is the original? It is not, as you describe it, the
Navier-Stokes equation.
> In a real collision the scattering take not place
> on a hexagonal grid, and the scattering directions are
> not bounded on a grid.
Agreed. The CA model on a hexagonal grid is an approximation.
> The *only* reason to use a CA is, that a CA has excelent
> properties for massive parallel computing.
This is _not_ the only reason to use CA.
> And it is realy surprising that such a lausy model has still some
> (qualitative) features of the real process. However,
> in the most cases the quatitative computed features, like
> pressure differ significant from the measured ones or from
> the computed values obtained by a FE solution.
>
> Starting with a CA and use it for the real process is like to take
> the a photograph of an image of a painted apple and eat it.
It seems like you are still stuck in the world of continuum models ...
Anyway, http://forum.wolframscience.com is probably a better place to
discuss this topic.
Cheers,
Paul
--
Paul Abbott Phone: +61 8 9380 2734
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